6. 2 SYMBOLS

Herebelow we list the parameters to be found in this chapter, indicating the relative symbols for greater clarity:

H_p = Polytropic head

Q = Volumetr ic capacity

N = Number of revolutions

Z = Gas compressibility factor

R = Universal constant of gas

T = Abs olute temperature

 n = Polytropic exponents

p = Compression ratio

Y = Specific gravity in operating conditions

h = Differential pressure dn the calibrated orifice

p = Absolute pres sure

δ_p = Pressure difference between delivery and suction

f = General function

f' = Function f derivative

β = Characteristic constant of the calibrated orifice

K = General constants

a = General constants

c = General constants

The index numbers "1" and "2" shall stand for the values referring to the suction and delivery conditions respectively. The same symbols, with a line above them, shall stand for the design values. For example:

T₁ = Absolute suction temperature

T₁ = Design absolute suction temperature

The following symbols should also be noted

DPT = Differential pressure transmitter

PT = Pressure transmitter

FIC = Regulator

S.P = Set-point

÷ = Divisor

x = Multiplier

– = Subtractor

= Function generator      

i/p = Electropneumatic converter

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